The present invention relates to breathing apparatus, and more specifically, to a connecting device for use with such apparatus which will enable two or more users to draw air or gas from a single gas container.
In many emergency situations such as in fire fighting and underwater operations, self-contained, portable breathing units are advantageously employed to give the users thereof substantially enhanced freedom of movement over what would be the case if such users were required to maintain connection through a hose extension to a source of air located at a distance from a work site.
Manufacturers of self-contained breathing units have been faced with the problem of balancing both the weight and encumbrancing nature of their devices with the desirability of providing as great an air supply and, hence, working time as possible for the user of such devices. As a consequence, it has been the practice to employ rather heavy steel tanks since such tanks are able to contain air at pressures on the order of 2,000 lbs. per square inch and yet remain substantially impervious to accidental puncture as well as remain resistant to high temperatures such as are encountered in mining operations and in fire fighting. In order to extend the useful capacity of the air storage tanks, it has been the practice to rely on the use of demand regulators which, in general, employ diaphragm chambers which are supplied with air from the tanks through a combination of a control valve and reduction chamber. With such arrangements, a user can withdraw the required quantity of air from the diaphragm chamber simply by inhaling since the air in the diaphragm chamber, by suitable regulation, will be at substantially atmospheric pressure.
As a safety feature, for example where there is a malfunction in the operation of the regulating device, a number of manufacturers provide a by-pass system where gas is supplied directly from the tank to the user with the gas being at the pressure of the tank. Such an arrangement is particularly necessary in underwater operations undertaken at considerable depths where the water pressure is sufficient to render a diaphragm type device inoperative.
A number of arrangements have been proposed to permit two or more users to draw on the same compressed air supply which is a circumstance which becomes necessary where, for example, a fire fighter comes upon an individual who has been trapped in a burning building or the air supply of one individual becomes exhausted while the necessity for oxygen is still present. In the field of underground mining, where there is an ever present danger of inhaling toxic gases, the capability of supplying two or more individuals from a single compressed air source is particularly important.
It has previously been proposed to simply provide a second hook-up to a source of supply to permit a second user to draw air from a compressed air tank. However, the operation required that the gas be supplied at free flow pressure which has the disadvantage that the air supply will be rapidly expended with much of the air being wasted due to the natural inability of the users to consume the air as it is escaping at high velocity. Other proposals, which are intended to permit the second user to draw air on a demand condition through the usual regulating device, have either required the users to inhale in unison or, alternatively, one of the users is required to inhale part of the air exhaled by the primary user. This can be particularly dangerous to the second user where the second user has been deprived of oxygen before his rescue or is suffering from injury or is in shock.
The connecting device of the present invention avoids the foregoing and other difficulties experienced in the prior art and provides a connection device which can be safely and efficiently utilized to connect a second user to a single gas supply and which will permit both users to draw air through a diaphragm regulator without one of the users being forced to inhale the exhaled air from the other user.
In a preferred embodiment, the present invention employs a metal body having a hollow interior chamber and three openings in the body all of which communicate with the chamber. One of the openings is connected to the source of gas while the other two openings are provided for supplying gas to a primary and a secondary user, where two such openings are employed. The primary opening utilizes a one-way flexible check valve which permits escape of gas from the chamber either under free flow conditions or on demand through the conventional regulator. This one-way valve prohibits exhaled air from being blown back into the chamber of the connecting device. The second and each subsequent opening are provided with a pair of valve means one of which is manually openable upon connection to the air conduit of the second user while the other valve means may be the same type of one-way check valve as is used in the first or primary opening.
With the connection device of the present invention, it will be possible for multiple users of a single gas source to draw air under regulated conditions without being subjected to inhaling each other's exhaled air. In addition, the connection device permits a single user to draw air either through the diaphragm regulator or under free flow conditions while permittIng a second user to quickly attach his hose to the connection device without interrupting air to the primary user.